Sensitized element, process of making same, and process for producing photographic images thereon



Patented Apr. 8, 1930 UNITED STATES '1,7s3,1os

ux'ra srr OFFICE "EnUAnD nnmanrmr EBIGH LEHMANN, or nrrnmsone, GERMANY SENSITIZED ELEMENT, PROCESS OF MAKING SAME, AND PROCESS FOB; PRODUCING PHOTOGZRAPHIC IMAGES THEREON No Drawing. Application filed April 26, 1927, Serial No. 186,832, and in Germany April 27, 1926.

My invention refers to means for producing photographic images on layers containing substances sensitive to light, and to the process of making such layers.

It is well known to those skilled in the art that certain diazo compounds are sensitive to light to such a degree that they can serve as starting products for the production of photographic images. To this efiect the solution of one of these diazo compounds is deposited on a suitable carrier, and the sensitive layer thus produced is then exposed to light. After exposure the image is developed by way of the coupling process. However, these methods involve serious drawbacks. The diazonium salts are extremely unstable and therefore require the paper prepaired with their aid to be exposed on the spot. Furthermore, these so-called diazo types furnish only very mat images lacklng in deeper shades, and the white portlons are unclear and colored.

According to the present invention all these drawbacks are substantially obviated by using diazonium compounds of p-amino diphenyl amine and its derivatives, for 1nstance sulphuretted, carboxylized, or nitrated compounds, or compounds having a methyl, ethyl, benzoyl group or the llke comblne'd with the nitrogen. 11 these compounds are extremely stable under seclusion of light and if they are deposited on a suitable carrier, for instance a textile carrier such as natural or artificial silk, a cellulose material, natural or artificial leather, ceramic articles and metals, the surfaces will show a fair sensitivityto light. If for instance paper prepared with one of these compounds is exposed to light under a lantern slide, after exposure 'during one half to five minutes in sunlight or in cor= responding artificial light, according to the density of the lantern slide, and after development with a phenolic body or some other suitable coupling agent, an image is obtained 45 which is distinguished by a correct reproduction, clear white portions, and good shading.

The coupling agent can also be deposited on the carrier together with the diazo compound in slightly acid solution and after exposure the image can be developed by immersing the carrier in soda solution or by acting thereon with ammonia as.

The invention further 0 ers another possibility. While in the process I mentioned above the portions of the layer which are not '55 decomposed are utilized in the roduction of the image, it is equally possi le to utilize those portions which have been decomposed by the action of the light. If, for instance, paper prepared in accordance with the process mentioned above is exposed to light un- :der a negative and the exposed layer is then placed in a solution of perchromic acid, it will be blackened at those places where the light has been acting thereon. After oxidation has come to an end the exposure is washed with water to remove the non-decomposed portions. The finished image shows a full brown tint. Other tints can be obtained by varying the starting product. i

In practising my invention I may for instance proceed as follows 18,4 grams p-amino diphenyl amine are dissolved in 100 ccms. of a 10 per cent muriatic acid, to which 800 ccms. water have been 7 added. Under constant stirring and cooling 7 grams sodium nitrite dissolved in 50 ccms. water are added little by little. The cleared solution is now filtered and the diazo compound is salted out. After sucking off and so pressing onto clay (in the dark) there is obtained a yellow crystal powder. 1 gram of this powder is dissolved in about 200 ccms. of water and the paper which is to be sensitized is placed on the solution to float thereon for about 10 to 20 seconds. Ifa fabric shallbe sensitized, it is soaked in the solution and dried in the dark. 4

The sensitive layer thus produced is exposed to light until the portions struck'by so the light are bleached out, whereupon it is placed in a slightly alkaline solution of a coupling agent such as ,B-naphtol. As soon as the image shows its full intensity, it is washed with water a few minutes.

When a positive image shall be produced from a negative one, the slightly over-exposed layer is placed in a 1 per cent solution of potash bich'romate and sulphuric acid, where it is left until the desired degree of blackening 100 2 v usages has been attained. It is then washed in a slow current of water until the diazo compound which was left undecomposed hasbeen cleared ofi. Various changes ma be made in the details described in the oregoing specification without degarting from the invention or sacrificing t e advantages thereof.

I claim L 4 1 1. As a new article of manufacture, a-

photographic layer comprising a diazo compound of p-amino diphenyl amine or its derivatives.

2. The process of producing a photo- 5 graphic layer comprising depositing a diazo compound of p-a'xilino diphen l amine, or a derivative thereof, on a suite 1e carrier.

3. The process 'of. producing a photographic image comprising depositing a diazo compound of p-amino dliphenyl amine or a derivative thereof on a suitable carrier exposing same to light to produce a photographic image thereon and subjecting same to oxidizing action for developing the mags. In testimony whereof I afiix my signature.

EDUARD EHRHARDT ERICK LEHMANN. 

